An ultrasonic probe composed of a plurality of piezoelectric transducers arranged so that an ultrasonic wave sending/receiving face forms a convex shape has been known conventionally (for example, see Patent Document 1). The ultrasonic probe can obtain a plurality of tomographic images and construct three-dimensional images by electronic scanning that is performed in an arrangement direction of the piezoelectric transducers (electronic scanning direction) and mechanical scanning that causes the piezoelectric transducers to move or swing in a direction different from the electronic scanning direction.
FIG. 7 is a perspective view showing a configuration of such an ultrasonic probe 101. An ultrasonic transducer body 103 has a plurality of piezoelectric transducers (not shown) arranged so as to form a convex shape, and transmits and receives ultrasonic waves. A swing shaft 104 is fixed to the ultrasonic transducer body 103, and supported swingably by a supporter (not shown). The swing shaft 104 is inserted in a swing shaft pulley 105, which is fixed to the swing shaft 104 by a pulley fastening screw 113. Further, an output shaft 107 of a motor 106 as a driving source is inserted in an output shaft pulley 108, which is fixed to the output shaft 107 by a pulley fastening screw 114. A belt 109 is wound around the swing shaft pulley 105 and the output shaft pulley 108.
The forward-backward rotation motion of the motor 106 is transmitted to the output shaft pulley 108, the belt 109, and the swing shaft pulley 105 in this order, which causes the ultrasonic transducer body 103 to swing around the swing shaft 104. By this motion, mechanical scanning by the swing of the ultrasonic transducer body 103 around the swing shaft 104 can be performed. Therefore, by combining the mechanical scanning with the electronic scanning performed by the plurality of the piezoelectric transducer arrays constituting the ultrasonic transducer body 103, it is possible to obtain certain tomographic images of a subject (not shown) and construct three-dimensional images.